"The most decorative clothing for the believer is the clothing of taqwa, and the finest one is faith. Allah, the Almighty and Glorified, said: 'and the clothing of taqwa, that is the best.'
As to the exterior clothing, it is a blessing from Allah, as it covers the nakedness of the children of Adam. lt is a grace granted by Allah to His servants, the children of Adam (AS), which He did not grant to other than them.
To the believers, it is a means to perform the duties imposed by Allah upon them. The best of your clothing is that which does not distract you from Allah, the Almighty and Glorified, rather it brings you nearer to thanking, remembering and obeying Him, and it does not bear you to conceit, hypocrisy, decoration, taking pride and boasting, as these are among the pests of the religion and bring cruelty to the heart.
When you put on your dress, remember Allah, the concealer of your sins by His mercy. Clothe your interior with truthfulness, as you dressed your exterior with your dress. Let your interior be under the protection of fear, and your exterior under the protection of obedience.
Take a lesson from the favour of Allah, the Almighty and Glorified, as He created the means for making clothes to conceal the apparent nakedness, and He opened the doors of repentance and imploring in order to cover the internal sins and evil characters.
Do not uncover anyone's faults, as Allah has covered your greater faults. Attend to your own faults, and forgive that whose state and affair do not concern you. Beware of perishing your life for the action of others, letting the others trade with your capital, while you destroy yourself.
Forgetting the sins is of the gravest punishments fraom Allah in this world, and of the most effective causes for the punishments in the Hereafter.
As long as the servant is engaged in his obedience to Allah, the Exalted, in recognizing his own defects and abandoning what is disgraceful in the religion of Allah, he will be isolated from the plagues, plunging in the sea of the mercy of Allah, the Almighty and Glorified, and will win the gems of the advantages of wisdom and expression. But as long as he is forgetting his sins, unfamiliar with his defects, resorting to his own might and force, he will never be successful."
Misbahush Shar'iah, sec. seven, on "Clothing"; from Adabus Salat by Imam Khomeini